The invention relates for example to a disc brake for an automotive vehicle of the type described and represented in French patent application FR-A1-3.004.500 which includes:
a brake disc which extends in a plane transverse to an axially is oriented axis of rotation of the disc;
a support being fixed with respect to a vehicle chassis;
at least one brake pad each of which includes a friction lining a friction transverse face of which cooperates with an associated braking track of the disc, the brake pad being axially slidingly mounted in the support between an active front position in which said friction face is bearing against the associated annular track of the disc, and an inactive rear position in which said friction face is axially spaced apart from said associated annular track of the disc, by a determined operating play;
at least one spring for elastically returning the brake pad to its inactive position, which is for example interposed between the brake pad and the support.
In a disc brake, the sliding of the brake pads to their active position is controlled by a piston. Both brake pads then strongly clamp the disc to slow its rotation. The braking operation is thus an active operation.
The brake pads are pushed back to their inactive position by the rotating disc. Thus, this is a passive operation.
However, the disc occasionally does not push back the brake pads with sufficiently force to space them apart sufficiently from the disc. This can for example happen when the sliding of the brake pads is of an insufficient, or even seized quality, or if the design creates some “recovery”.
Even though the brake pads are no longer actively tightened against the disc, each of the annular tracks of the latter, nonetheless, permanently rubs against the friction lining carried by the associated brake pad. The friction linings thus undergo a premature non-functional wear.
Moreover, this permanent rubbing is likely to cause a warm-up damageable for some members of the disc brake.
This permanent rubbing also causes the appearance of a residual torque which comes against the disc rotation. This increases the vehicle consumption, while reducing the vehicle performance.
To solve these wear and warm-up problems, the above-mentioned document provides a disc brake wherein the elastic return spring includes means for taking up a wear play of the friction lining of the brake pad which are plastically deformed when the stroke of the brake pad to its active position is higher than said determined operating play.
To that end, the elastic return spring, which is interposed between the fixed support of the disc brake and an associated brake pad, includes at least one axially orientated segment which is elastically deformable by tension between a standby state and a maximum elongation state the value of which is equal to the determined operating play, the spring including at least one plastically deformable segment, under the effect of an axial tensile strain, forming said means for taking up the wear play, this plastically deformable segment being shaped to be plastically elongated when the stroke of the brake pad up to its active position is higher than the determined operating play.
According to the embodiment provided in this document, the elastic return spring includes in particular a portion for attaching the elastic return spring to the fixed support, and a rigid branch with a generally axial orientation the free end segment of which is shaped to cooperate with the associated brake pad. According to another known design, the free end segment is attached to the brake pad.
Such designs result in complex mounting and assembly to ensure cooperation of the return spring with the brake pad, or its attachment to the brake pad.
These drawbacks also exist when the return spring does not include a plastically deformable segment.